Alpha crystalline form of strontium ranelate

ABSTRACT

Alpha crystalline form of strontium ranelate of formula (I): 
                         
characterised by its powder X-ray diffraction diagram and by a water content of from 22 to 24%.
 
     Medicinal products containing the same which are useful in the treatment of osteoporosis and arthrosis.

BACKGROUND OF THE INVENTION

Strontium ranelate, represented by formula (I):

or the distrontium salt of 5-[bis(carboxymethyl)amino]-3-carboxymethyl-4-cyano-2-thiophenecarboxylic acid, and its hydrates have very valuable pharmacological and therapeutic properties, especially pronounced anti-osteoporotic properties, making these compounds useful in the treatment and prevention of bone diseases.

Strontium ranelate and its hydrates also have properties making them useful in the treatment and prevention of arthrosis.

DESCRIPTION OF THE PRIOR ART

The preparation and therapeutic use of strontium ranelate and its tetrahydrate, heptahydrate and octahydrate have been described in the European Patent Specification EP 0 415 850.

The use of strontium ranelate in the prevention and treatment of arthrosis has been described in the European Patent Specification EP 0 813 869.

DETAILED DESCRIPTION OF THE INVENTION

The Applicant has now found that strontium ranelate can be obtained in a well-defined crystalline form which is perfectly reproducible and which, by virtue of that fact, has valuable characteristics in terms of filtration and ease of formulation.

More specifically, the present invention relates to the alpha crystalline form of strontium ranelate, characterised by a water content of from 22 to 24% and by the following powder X-ray diffraction diagram measured using a PANalytical X'Pert Pro diffractometer together with an X'Celerator detector and expressed in terms of ray position (Bragg's angle 2 theta, expressed in degrees), ray height (expressed in counts), ray area (expressed in counts×degrees), ray width at half-height (“FWHM”, expressed in degrees) and interplanar distance d (expressed in Å):

Angle 2 Area theta Height (counts × FWHM Interplanar Ray no. (degrees) (counts) degrees) (degrees) distance (Å) 1 7.6 4527 448 0.1004 11.649 2 8.0 1438 142 0.1004 11.069 3 8.3 3522 349 0.1004 10.642 4 8.6 11347 1123 0.1004 10.272 5 8.9 7332 726 0.1004 9.889 6 11.0 1047 104 0.1004 8.072 7 11.3 1655 164 0.1004 7.840 8 12.0 2186 216 0.1004 7.355 9 13.2 2887 381 0.1338 6.703 10 13.5 1705 169 0.1004 6.557 11 14.1 154 30 0.2007 6.275 12 14.7 803 79 0.1004 6.035 13 14.9 1346 178 0.1338 5.942 14 15.8 1556 154 0.1004 5.613 15 16.0 3339 441 0.1338 5.527 16 16.7 1845 183 0.1004 5.308 17 17.3 2835 281 0.1004 5.127 18 17.6 1252 124 0.1004 5.049 19 18.0 2183 216 0.1004 4.939 20 19.2 2303 228 0.1004 4.622 21 19.8 1298 128 0.1004 4.475 22 20.3 788 78 0.1004 4.373 23 20.6 1039 103 0.1004 4.317 24 21.1 882 116 0.1338 4.211 25 21.7 390 38 0.1004 4.103 26 22.3 1919 253 0.1338 3.990 27 22.7 1805 179 0.1004 3.923 28 23.0 4043 467 0.1171 3.861 29 23.5 650 86 0.1338 3.792 30 24.0 8677 1002 0.1171 3.711 31 24.7 229 30 0.1338 3.600 32 25.1 1246 164 0.1338 3.543 33 25.6 1659 219 0.1338 3.473 34 25.9 1773 175 0.1004 3.442 35 26.3 695 69 0.1004 3.385 36 26.6 401 46 0.1171 3.355 37 27.0 2800 370 0.1338 3.300 38 27.6 1415 140 0.1004 3.230 39 28.0 3250 429 0.1338 3.186 40 28.4 1513 250 0.1673 3.144 41 29.1 1456 144 0.1004 3.068 42 29.6 1943 192 0.1004 3.022 43 30.1 3637 540 0.1506 2.967 44 30.5 707 117 0.1673 2.929 45 30.9 596 59 0.1004 2.897 46 31.8 577 76 0.1338 2.816 47 32.0 1080 107 0.1004 2.796 48 32.5 512 51 0.1004 2.756 49 32.9 1268 167 0.1338 2.726 50 33.4 1180 117 0.1004 2.685

The invention relates also to a process for the preparation of the alpha crystalline form of strontium ranelate, characterised in that a solution of strontium ranelate or a hydrate thereof in water is heated to reflux and then cooled until crystallisation is complete, and the product is collected by filtration.

-   -   In the preparation process according to the invention it is         possible to use strontium ranelate or a hydrate thereof obtained         by any process, for example strontium ranelate octahydrate         obtained by the preparation process described in the Patent         Specification EP0415 850.     -   An advantage of obtaining the said crystalline form is to allow         especially rapid and efficient filtration and also the         preparation of pharmaceutical formulations of consistent and         reproducible composition, which is especially advantageous when         the formulations are intended for oral administration.     -   The form thereby obtained is sufficiently stable to allow its         storage for an extended period without particular conditions in         terms of temperature, light, humidity or oxygen levels.

The invention relates also to pharmaceutical compositions comprising as active ingredient the alpha crystalline form of strontium ranelate together with one or more appropriate, inert and non-toxic excipients. Among the pharmaceutical compositions according to the invention there may be mentioned, more especially, those that are suitable for oral, parenteral (intravenous or subcutaneous) or nasal administration, tablets or dragées, granules, sublingual tablets, capsules, lozenges, suppositories, creams, ointments, dermal gels, injectable preparations, drinkable suspensions and chewing gums.

The useful dosage can be varied according to the nature and severity of the disorder, the administration route and the age and weight of the patient. The dosage varies from 0.2 to 10 g per day in one or more administrations.

The Examples that follow-illustrate the invention.

The X-ray powder diffraction spectrum was measured under the following experimental conditions:

-   -   PANalytical X'Pert Pro diffractometer, X'Celerator detector,     -   voltage 45 kV, intensity 40 mA,     -   mounting θ-θ,     -   Kβ (Ni) filter,     -   incident-beam and diffracted-beam Soller slit: 0.04 rad,     -   divergence slits: automatic, irradiated length: 10 mm,     -   mask: 10 mm,     -   antiscatter slit: 1/2°,     -   measurement mode: continuous from 3° to 34°, in increments of         0.017°,     -   measurement time per step: 31.1 s,     -   total time: 8 min 07 s,     -   measurement speed: 0.068°/s,     -   spinner: turning at 1 revolution/s,     -   measurement temperature: ambient.

Example 1 Alpha Crystalline form of Strontium Ranelate

200 g of strontium ranelate octahydrate obtained according to the process described in Patent Specification EP 0 415 850 are mixed with 2 liters of water and heated to reflux.

The mixture is then cooled to 20° C.

The solid obtained is collected by filtration.

The water content of the product obtained, determined by loss on drying, is from 22 to 24%, which corresponds to from 8.1 to 9 molecules of water per molecule of strontium ranelate.

X-Ray Powder Diffraction Diagram:

The X-ray powder diffraction profile (diffraction angles) of the alpha form of strontium ranelate is given by the significant rays collated in the following table:

Angle 2 Area theta Height (counts × FWHM Interplanar Ray no. (degrees) (counts) degrees) (degrees) distance (Å) 1 7.6 4527 448 0.1004 11.649 2 8.0 1438 142 0.1004 11.069 3 8.3 3522 349 0.1004 10.642 4 8.6 11347 1123 0.1004 10.272 5 8.9 7332 726 0.1004 9.889 6 11.0 1047 104 0.1004 8.072 7 11.3 1655 164 0.1004 7.840 8 12.0 2186 216 0.1004 7.355 9 13.2 2887 381 0.1338 6.703 10 13.5 1705 169 0.1004 6.557 11 14.1 154 30 0.2007 6.275 12 14.7 803 79 0.1004 6.035 13 14.9 1346 178 0.1338 5.942 14 15.8 1556 154 0.1004 5.613 15 16.0 3339 441 0.1338 5.527 16 16.7 1845 183 0.1004 5.308 17 17.3 2835 281 0.1004 5.127 18 17.6 1252 124 0.1004 5.049 19 18.0 2183 216 0.1004 4.939 20 19.2 2303 228 0.1004 4.622 21 19.8 1298 128 0.1004 4.475 22 20.3 788 78 0.1004 4.373 23 20.6 1039 103 0.1004 4.317 24 21.1 882 116 0.1338 4.211 25 21.7 390 38 0.1004 4.103 26 22.3 1919 253 0.1338 3.990 27 22.7 1805 179 0.1004 3.923 28 23.0 4043 467 0.1171 3.861 29 23.5 650 86 0.1338 3.792 30 24.0 8677 1002 0.1171 3.711 31 24.7 229 30 0.1338 3.600 32 25.1 1246 164 0.1338 3.543 33 25.6 1659 219 0.1338 3.473 34 25.9 1773 175 0.1004 3.442 35 26.3 695 69 0.1004 3.385 36 26.6 401 46 0.1171 3.355 37 27.0 2800 370 0.1338 3.300 38 27.6 1415 140 0.1004 3.230 39 28.0 3250 429 0.1338 3.186 40 28.4 1513 250 0.1673 3.144 41 29.1 1456 144 0.1004 3.068 42 29.6 1943 192 0.1004 3.022 43 30.1 3637 540 0.1506 2.967 44 30.5 707 117 0.1673 2.929 45 30.9 596 59 0.1004 2.897 46 31.8 577 76 0.1338 2.816 47 32.0 1080 107 0.1004 2.796 48 32.5 512 51 0.1004 2.756 49 32.9 1268 167 0.1338 2.726 50 33.4 1180 117 0.1004 2.685

Example 2 Pharmaceutical Composition

Formula for the preparation of 1000 tablets each containing 0.5 g of active ingredient:

Compound of Example 1 658 g Sodium carboxymethyl starch 25.5 g Microcrystalline cellulose 119.4 g Povidone 38 g Anhydrous colloidal silica 1.5 g Magnesium stearate 7.6 g 

1. An alpha crystalline form of strontium ranelate of formula (I):


2. The alpha crystalline form of strontium ranelate of claim 1 having a powder X-ray diffraction diagram exhibiting peaks at 7.6, 8.0, 8.6, 11.3, 12.0 and 13.5 deg 2 theta.
 3. A pharmaceutical composition comprising as active ingredient the alpha crystalline form of strontium ranelate of claim 1 in combination with one or more pharmaceutically acceptable, inert and non-toxic carriers.
 4. A method of treating a living animal body afflicted with osteoporosis, comprising the step of administering to the living animal body an amount of a compound of claim 1 which is effective for alleviation of the condition.
 5. A method of treating a living animal body afflicted with arthrosis, comprising the step of administering to the living animal body an amount of a compound of claim 1 which is effective for alleviation of the condition. 